Objective: To create and validate an objective assessing tool to diagnose and monitor HFS and the efficacy of its treatments.

Background: Hemifacial spasm (HFS), is characterized by unilateral, intermittent contractions of the muscles of facial expression. Periorbital muscles are commonly involved [1], even leading to involuntary eyelid closure. Frequently its evolution may cause the involvement of an increasing number of muscles and patients at a first assessment can present a wide range of clinical features. Botulinum toxin (BoNT) is the therapy of choice, but evidence from controlled clinical trials are few. There is a broad variety of rating scales used in clinical studies and no consensus has been reached on how to assess the disorder and its treatment outcome.[2]

Methods: Prospective observational cohort study protocol approved by the local ethics advisory committee (CEAS Umbria). A group of Neurologists with experience on HFS treatment, outpointed from a list of phenomenological aspects potentially related to HFS, three main features (localisation, intensity and frequency of involuntary muscular contractions). Four independent drafts of the scale were created an then merged to obtain the final version of HFS Grading Scale (HFSGS).

Results: Intra-rater reproducibility ranged between ICC 0.73 (95% CI=0.54-0.86) and 0.83 (0.68-0.92), inter-rater reproducibility between 0.62 (95% CI=0.44-0.77) and 0.82 (0.69-0.90). A significative correlation (Spearman) was also observed with another rating scale previously tested on a BoNT efficacy study [3].

Conclusions: We built an objective, valid and reliable scale for the assessment of HFS. Our results support the potential use of HFSGS as a monitoring tool of BoNT treatment efficacy over time.

References: [1] R.G. Auger, J.P. Whisnant, Hemifacial spasm in Rochester and Olmstead County, Minnesota, 1960 to 1984, Arch. Neurol. 47 (1990) 1233–1234. [2] B. Wabbels, P. Roggenkamper, Botulinum toxin in hemifacial spasm: the challenge to assess the effect of treatment, Neural Transm (2012) 119:963–980. [3] Chen RS, Lu CS, Tsai CH (1996) Botulinum toxin A injection in the treatment of hemifacial spasm. Acta Neurol Scand 94(3):207– 211.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/assessing-hemifacial-spasm-the-hfsg-scale/